US4785463A
Expired / Lapsed
US
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Digital global positioning system receiver
Assignee: Motorola Solutions Inc
•
Filing: 1985-09-03
•
Granted: 1988-11-15
•
Expires: 2005-09-03
Abstract
Abstract A digital receiver for GPS C/A-code signals is described. The GPS receiver of the present invention provides reception and tracking a plurality of satellites simultaneously, using four separate receiver channels. The GPS receiver of the present invention includes an analog front-end for selecting and frequency translating the received GPS signal. The GPS receiver further includes a highspeed digital signal processor for recovering the despread data of the GPS signal. The baseband signal is further processed by a general purpose digital signal processor for signal search, tracking, and data recovery operations, and a microprocessor provides overall receiver control, and interface with the operator of the GPS receiver.
Inventors
- 👤 Robert V. Janc
- 👤 Steven C. Jasper
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 19:36
CPC Classifications
G; G01; G01S; G01S19/00; G01S19/01; G01S19/13; G01S19/24; G01S19/29; G01S11/00; G01S11/02; G01S11/10
Claims Analysis
Total Claims: 44
Claim 1
Independent Claim
219 words
An improved substantially digital receiver apparatus for the reception of one or more direct-sequence-coded spread spectrum signals, which exhibit substantially equal carrier frequencies, except for Doppler shifting, said apparatus comprising: (a) first means for coupling a wideband radio frequency (RF) signal containing said spread spectrum signals to said receiving apparatus; (b) second means, including preselector and down-converting means, coupled to said first means, for selecting a composite signal containing said spread spectrum signals from said wide-band RF signal and for frequency-translating said composite signal to an intermediate frequency; (c) digitizing means, coupled to said second means, for converting said translated composite signal to a digital composite signal, at a predetermined sampling rate, wherein the predetermined sampling rate is determined according to the relationship: m f s =4f i wherein f i is said intermediate frequency and f s is the predetermined sampling rate; (d) first processing means, coupled to said digitizing means, for separating and despreading each of said spread spectrum signals from said digital composite signal, and for deriving a prompt and auxiliary late-early signal corresponding to each spread-spectrum signal; and (e) second processing means, coupled to said first processing means, providing for each desired signal, code delay search and tracking and carrier search and tracking processing for each of said doppler shifted signals, and data recovery processing.
Claim 2
Dependent Claim
219 words
An improved substantially digital receiver apparatus for the reception of one or more direct-sequence-coded spread spectrum signals, which exhibit substantially equal carrier frequencies, except for Doppler shifting, said apparatus comprising: (a) first means for coupling a wideband radio frequency (RF) signal containing said spread spectrum signals to said receiving apparatus; (b) second means, including preselector and down-converting means, coupled to said first means, for selecting a composite signal containing said spread spectrum signals from said wide-band RF signal and for frequency-translating said composite signal to an intermediate frequency; (c) digitizing means, coupled to said second means, for converting said translated composite signal to a digital composite signal, at a predetermined sampling rate, wherein the predetermined sampling rate is determined according to the relationship: m f s =4f i wherein f i is said intermediate frequency and f s is the predetermined sampling rate; (d) first processing means, coupled to said digitizing means, for separating and despreading each of said spread spectrum signals from said digital composite signal, and for deriving a prompt and auxiliary late-early signal corresponding to each spread-spectrum signal; and (e) second processing means, coupled to said first processing means, providing for each desired signal, code delay search and tracking and carrier search and tracking processing for each of said doppler shifted signals, and data recovery processing.
Claim 3
Dependent Claim
29 words
The apparatus as recited in claim 1 wherein said second means includes a ceramic filter for selecting a band of frequencies corresponding to the desired direct-sequence-coded spread spectrum signal.
Claim 4
Dependent Claim
16 words
The apparatus as recited in claim 1 wherein said digitizing means is a flash A/D converter.
Claim 5
Dependent Claim
25 words
The apparatus as recited in claim 1 wherein said first processing means includes means for quadrature mixing said digital composite signal to approximately zero frequency.
Claim 6
Dependent Claim
26 words
The apparatus as recited in claim 1 wherein said first processing means includes decimating filters for sample rate reduction of the auxiliary prompt and late/early signals.
Claim 7
Dependent Claim
13 words
The apparatus as recited in claim 4 wherein said decimating filters are multiplierless.
Claim 8
Dependent Claim
17 words
The apparatus as recited in claim 1 wherein said first processing means includes a pseudorandom code generator.
Claim 9
Dependent Claim
21 words
The apparatus as recited in claim 1 wherein said second processing means includes means for data bit synchronization, and data detection.
Claim 10
Dependent Claim
17 words
The apparatus as recited in claim 1 wherein said second processing means includes a carrier recovery loop.
Claim 11
Dependent Claim
18 words
The apparatus as recited in claim 1 wherein said second processing means includes a Costas carrier recovery loop.
Claim 12
Dependent Claim
19 words
The apparatus as recited in claim 1 wherein said second processing means includes means for automatic gain control (AGC).
Claim 13
Dependent Claim
20 words
The apparatus as recited in claim 1 wherein said second processing means includes delay-locked loop means for code delay tracking.
Claim 14
Dependent Claim
158 words
An improved method for digitally receiving one or more direct-sequence-coded spread spectrum signals, which exhibit substantially equal carrier frequencies, except for Doppler shifting, said method comprising the steps of: (a) coupling a wideband radio frequency (RF) signal containing at least said direct-sequence-coded spread spectrum signals to said receiving apparatus; (b) selecting a composite signal containing said spread spectrum signals from said wide-band RF signal; (c) converting said selected composite signal to a digital composite signal, at a predetermined sampling rate determined according to the relationship: f s =4f i ; wherein f i is an intermediate frequency; (d) separating and despreading each of said direct-sequence-coded spread spectrum signals from said digital composite signal, including generating a prompt pseudorandom code signal and a late/early signal corresponding to each direct-sequence-coded spread spectrum signal; and (e) code delay searching and tracking and carrier searching and tracking the doppler-shifted signal corresponding to each desired spread spectrum signal, and recovering a data signal.
Claim 15
Dependent Claim
158 words
An improved method for digitally receiving one or more direct-sequence-coded spread spectrum signals, which exhibit substantially equal carrier frequencies, except for Doppler shifting, said method comprising the steps of: (a) coupling a wideband radio frequency (RF) signal containing at least said direct-sequence-coded spread spectrum signals to said receiving apparatus; (b) selecting a composite signal containing said spread spectrum signals from said wide-band RF signal; (c) converting said selected composite signal to a digital composite signal, at a predetermined sampling rate determined according to the relationship: f s =4f i ; wherein f i is an intermediate frequency; (d) separating and despreading each of said direct-sequence-coded spread spectrum signals from said digital composite signal, including generating a prompt pseudorandom code signal and a late/early signal corresponding to each direct-sequence-coded spread spectrum signal; and (e) code delay searching and tracking and carrier searching and tracking the doppler-shifted signal corresponding to each desired spread spectrum signal, and recovering a data signal.
Claim 16
Dependent Claim
26 words
The method as recited in claim 13 wherein said selecting step includes the steps of filtering, amplifying, and frequency-translating said composite signal to an intermediate frequency.
Claim 17
Dependent Claim
109 words
The method as recited in claim 13 wherein said separating and despreading step includes the steps of: (a) generating a prompt pseudorandom code signal and a late/early pseudorandom code corresponding to each desired spread-spectrum signal; (b) multiplying the prompt pseudorandom code by the digital composite signal to generate a first digital product signal; (c) filtering the first digital product signal to generate a prompt signal; (d) multiplying the late/early pseudorandom code by the digital composite signal to generate a second digital product signal; (e) filtering the second digital product signal to generate an auxiliary late/early signal; and (f) outputting said prompt and said auxiliary late/early signals for further processing.
Claim 18
Dependent Claim
219 words
An improved method for digitally receiving one or more direct-sequence-coded spread spectrum signals, which exhibit substantially equal carrier frequencies, except for Doppler shifting, said method comprising the steps of: (a) coupling a wideband radio frequency (RF) signal containing at least said direct-sequence-coded spread spectrum signals to said receiving apparatus; (b) selecting a composite signal containing said spread spectrum signals from said wide-band RF signal; (c) converting said selected composite signal to a digital composite signal, at a predetermined sampling rate; (d) separating and despreading each of said direct-sequence-coded spread spectrum signals from said digital composite signal, including generating a prompt pseudorandom code signal and a late/early signal corresponding to each direct-sequence-coded spread spectrum signal; (e) estimating a code-delay for the desired direct-sequence-coded spread spectrum signal, and generating a pseudorandom code signal corresponding to said delay; (f) measuring the spectral power of the prompt signal for the current code delay generated by said separating and despreading step; (g) comparing the power values measured in said measuring step to a predetermined threshold value, wherein a power value exceeding said threshold value indicates the proper code delay and doppler shifted carrier frequency; and (h) incrementing the code delay and repeating steps (e) through (h) until a proper code delay and doppler shifted carrier frequency is found and recovering a data signal therefrom.
Claim 19
Dependent Claim
219 words
An improved method for digitally receiving one or more direct-sequence-coded spread spectrum signals, which exhibit substantially equal carrier frequencies, except for Doppler shifting, said method comprising the steps of: (a) coupling a wideband radio frequency (RF) signal containing at least said direct-sequence-coded spread spectrum signals to said receiving apparatus; (b) selecting a composite signal containing said spread spectrum signals from said wide-band RF signal; (c) converting said selected composite signal to a digital composite signal, at a predetermined sampling rate; (d) separating and despreading each of said direct-sequence-coded spread spectrum signals from said digital composite signal, including generating a prompt pseudorandom code signal and a late/early signal corresponding to each direct-sequence-coded spread spectrum signal; (e) estimating a code-delay for the desired direct-sequence-coded spread spectrum signal, and generating a pseudorandom code signal corresponding to said delay; (f) measuring the spectral power of the prompt signal for the current code delay generated by said separating and despreading step; (g) comparing the power values measured in said measuring step to a predetermined threshold value, wherein a power value exceeding said threshold value indicates the proper code delay and doppler shifted carrier frequency; and (h) incrementing the code delay and repeating steps (e) through (h) until a proper code delay and doppler shifted carrier frequency is found and recovering a data signal therefrom.
Claim 20
Dependent Claim
23 words
The method as recited in claim 16, wherein said spectral power measuring step comprises a Fast Fourier Transform (FFT) aided spectral power measurement.
Claim 21
Dependent Claim
35 words
The method as recited in claim 15 wherein said filtering the first digital product signal step further includes the step of decimating said first product signal to reduce the sampling rate of said prompt signal.
Claim 22
Dependent Claim
35 words
The method as recited in claim 15 wherein said filtering the second digital product signal step further includes the step of decimating said second product signal to reduce the sampling rate of said late/early signal.
Claim 23
Dependent Claim
236 words
An improved substantially digital receiver apparatus for the reception of one or more global positioning system (GPS) coarse acquisition/clear access (C/A) coded spread spectrum signals, which exhibit substantially equal carrier frequencies (except for Doppler shifting); said apparatus comprising: (a) first means for coupling a wideband radio frequency (RF) signal containing said GPS C/A coded spread spectrum signals to said receiving apparatus; (b) second means, including preselector and down-converting means, coupled to said first means, for selecting a composite signal containing said GPS C/A coded spread spectrum signals from said wide-band RF signal and for frequency-translating said composite signal to an intermediate frequency; (c) digitizing means, coupled to said second means, for converting said translated composite signal to a digital composite signal, at a predetermined sampling rate, wherein the predetermined sampling rate is determined according to the relationship: f s =4f i wherein f i is said intermediate frequency and f s is the predetermined sampling rate; (d) first processing means, coupled to said digitizing means, for separating and despreading each of said GPS C/A coded spread spectrum signals from said digitial composite signal, and for deriving prompt and auxiliary late-early signal corresponding to each spread-spectrum signal; and (e) second processing means, coupled to said first processing means, providing for each desired signal, carrier search and tracking and code delay search and tracking processing in response to said prompt and auxiliary late-early signals, and data recovery processing.
Claim 24
Dependent Claim
236 words
An improved substantially digital receiver apparatus for the reception of one or more global positioning system (GPS) coarse acquisition/clear access (C/A) coded spread spectrum signals, which exhibit substantially equal carrier frequencies (except for Doppler shifting); said apparatus comprising: (a) first means for coupling a wideband radio frequency (RF) signal containing said GPS C/A coded spread spectrum signals to said receiving apparatus; (b) second means, including preselector and down-converting means, coupled to said first means, for selecting a composite signal containing said GPS C/A coded spread spectrum signals from said wide-band RF signal and for frequency-translating said composite signal to an intermediate frequency; (c) digitizing means, coupled to said second means, for converting said translated composite signal to a digital composite signal, at a predetermined sampling rate, wherein the predetermined sampling rate is determined according to the relationship: f s =4f i wherein f i is said intermediate frequency and f s is the predetermined sampling rate; (d) first processing means, coupled to said digitizing means, for separating and despreading each of said GPS C/A coded spread spectrum signals from said digitial composite signal, and for deriving prompt and auxiliary late-early signal corresponding to each spread-spectrum signal; and (e) second processing means, coupled to said first processing means, providing for each desired signal, carrier search and tracking and code delay search and tracking processing in response to said prompt and auxiliary late-early signals, and data recovery processing.
Claim 25
Dependent Claim
30 words
The apparatus as recited in claim 20 wherein said second means includes a ceramic filter for selecting a band of frequencies corresponding to the desired GPS C/A spread spectrum signal.
Claim 26
Dependent Claim
16 words
The apparatus as recited in claim 20 wherein said digitizing means is a flash A/D converter.
Claim 27
Dependent Claim
25 words
The apparatus as recited in claim 20 wherein said first processing means includes means for quadrature mixing said digital composite signal to approximately zero frequency.
Claim 28
Dependent Claim
27 words
The apparatus as recited in claim 20 wherein said first processing means includes a decimating filters for sample rate reduction of said prompt and auxiliary late/early signals.
Claim 29
Dependent Claim
13 words
The apparatus as recited in claim 23 wherein said decimating filters are multiplierless.
Claim 30
Dependent Claim
17 words
The apparatus as recited in claim 20 wherein said first processing means includes a C/A code generator.
Claim 31
Dependent Claim
17 words
The apparatus as recited in claim 20 wherein said second processing means includes a carrier recovery loop.
Claim 32
Dependent Claim
18 words
The apparatus as recited in claim 20 wherein said second processing means includes a Costas carrier recovery loop.
Claim 33
Dependent Claim
19 words
The apparatus as recited in claim 20 wherein said second processing means includes means for automatic gain control (AGC).
Claim 34
Dependent Claim
20 words
The apparatus as recited in claim 20 wherein said second processing means includes delay-locked loop means for code delay tracking.
Claim 35
Dependent Claim
21 words
The apparatus as recited in claim 20 wherein said second processing means includes means for data bit synchronization, and data detection.
Claim 36
Independent Claim
202 words
A method for the reception of one or more global positioning system (GPS) coarse acquisition/clear access (C/A) coded spread spectrum signals, which exhibit substantially equal carrier frequencies (except for Doppler shifting); said method comprising the steps of: (a) coupling a wideband radio frequency (RF) signal containing said GPS C/A coded spread spectrum signals to said receiving apparatus; (b) selecting a composite signal containing said GPS C/A coded spread spectrum signals from said wide-band RF signal and for frequency-translating said composite signal to an intermediate frequency; (c) converting said translated composite signal to a digital composite signal, at a predetermined sampling rate, wherein the predetermined sampling rate is determined according to the relationship: f s 4f i wherein f i is said intermediate frequency and f s is the predetermined sampling rate; (d) separating and despreading each of said GPS spread spectrum signals from said digitial composite signal, including generating a prompt C/A code signal and a late/early C/A code signal and deriving a prompt and auxiliary late-early signal corresponding to each GPS spread-spectrum signal; and (e) code delay searching and tracking and carrier searching and tracking the doppler-shifter signal corresponding to each desired GPS spread spectrum signal, and recovering a data signal.
Claim 37
Independent Claim
202 words
A method for the reception of one or more global positioning system (GPS) coarse acquisition/clear access (C/A) coded spread spectrum signals, which exhibit substantially equal carrier frequencies (except for Doppler shifting); said method comprising the steps of: (a) coupling a wideband radio frequency (RF) signal containing said GPS C/A coded spread spectrum signals to said receiving apparatus; (b) selecting a composite signal containing said GPS C/A coded spread spectrum signals from said wide-band RF signal and for frequency-translating said composite signal to an intermediate frequency; (c) converting said translated composite signal to a digital composite signal, at a predetermined sampling rate, wherein the predetermined sampling rate is determined according to the relationship: f s 4f i wherein f i is said intermediate frequency and f s is the predetermined sampling rate; (d) separating and despreading each of said GPS spread spectrum signals from said digitial composite signal, including generating a prompt C/A code signal and a late/early C/A code signal and deriving a prompt and auxiliary late-early signal corresponding to each GPS spread-spectrum signal; and (e) code delay searching and tracking and carrier searching and tracking the doppler-shifter signal corresponding to each desired GPS spread spectrum signal, and recovering a data signal.
Claim 38
Dependent Claim
26 words
The method as recited in claim 32 wherein said selecting step includes the steps of filtering, amplifying, and frequency-translating said composite signal to an intermediate frequency.
Claim 39
Dependent Claim
109 words
The method as recited in claim 32 wherein said separating and despreading step includes the steps of: (a) generating a prompt C/A code signal and a late/early C/A code corresponding to each desired spread-spectrum signal; (b) multiplying the prompt C/A code by the digital composite signal to generate a first digital product signal; (c) filtering the first digital product signal to generate a prompt signal; (d) multiplying the late/early C/A code by the digital composite signal to generate a second digital product signal; (e) filtering the second digital product signal to generate an auxiliary late/early signal; and (f) outputting said prompt and said auxiliary late/early signals for further processing.
Claim 40
Independent Claim
268 words
A method for the reception of one or more global positioning system (GPS) coarse acquisition/clear access (C/A) coded spread spectrum signals, which exhibit substantially equal carrier frequencies, except for Doppler shifting, said method comprising the steps of: (a) coupling a wideband radio frequency (RF) signal containing at least said GPS C/A coded spread spectrum signals to said receiving apparatus; (b) selecting a composite signal containing said GPS C/A coded spread spectrum signals from said wide-band RF signal and frequency translating said composite signal to an intermediate frequency; (c) converting said selected composite signal to a digital composite signal, at a predetermined sampling rate determined according to the relationship: f s =4f i ; wherein f i is said intermediate frequency; (d) separating and despreading each of said GPS spread spectrum signals from said digital composite signal, including generating a prompt C/A code signal and an late/early C/A signal and deriving a prompt and auxiliary late/early signal corresponding to each GPS spread spectrum signal; (e) estimating a code-delay for the desired GPS spread spectrum signal, and generating a C/A code signal corresponding to said delay; (f) measuring the spectral power of the prompt signal for the current code delay generated by said separating and despreading step; (g) comparing the power values measured in said measuring step to a predetermined threshold value, wherein a power value exceeding said threshold value indicates the proper code delay and doppler shifted carrier frequency; and (h) incrementing the code delay and repeating steps (e) through (h) until a proper code delay and doppler shifted carrier frequency is found and recovering a data signal therefrom.
Claim 41
Independent Claim
268 words
A method for the reception of one or more global positioning system (GPS) coarse acquisition/clear access (C/A) coded spread spectrum signals, which exhibit substantially equal carrier frequencies, except for Doppler shifting, said method comprising the steps of: (a) coupling a wideband radio frequency (RF) signal containing at least said GPS C/A coded spread spectrum signals to said receiving apparatus; (b) selecting a composite signal containing said GPS C/A coded spread spectrum signals from said wide-band RF signal and frequency translating said composite signal to an intermediate frequency; (c) converting said selected composite signal to a digital composite signal, at a predetermined sampling rate determined according to the relationship: f s =4f i ; wherein f i is said intermediate frequency; (d) separating and despreading each of said GPS spread spectrum signals from said digital composite signal, including generating a prompt C/A code signal and an late/early C/A signal and deriving a prompt and auxiliary late/early signal corresponding to each GPS spread spectrum signal; (e) estimating a code-delay for the desired GPS spread spectrum signal, and generating a C/A code signal corresponding to said delay; (f) measuring the spectral power of the prompt signal for the current code delay generated by said separating and despreading step; (g) comparing the power values measured in said measuring step to a predetermined threshold value, wherein a power value exceeding said threshold value indicates the proper code delay and doppler shifted carrier frequency; and (h) incrementing the code delay and repeating steps (e) through (h) until a proper code delay and doppler shifted carrier frequency is found and recovering a data signal therefrom.
Claim 42
Dependent Claim
23 words
The method as recited in claim 35, wherein said spectral power measuring step comprises a Fast Fourier Transform (FFT) aided spectral power measurement.
Claim 43
Dependent Claim
35 words
The method as recited in claim 34 wherein said filtering the first digital product signal step further includes the step of decimating said first product signal to reduce the sampling rate of said prompt signal.
Claim 44
Dependent Claim
35 words
The method as recited in claim 34 wherein said filtering the second digital product signal step further includes the step of decimating said second product signal to reduce the sampling rate of said late/early signal.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1991-11-15 | 1992-05-16 | 1992-11-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-11-15 | 1996-05-16 | 1996-11-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-11-15 | 2000-05-16 | 2000-11-15 | $7700.00 | Window Closed / Lapsed |